Судя по времени перехода, ночной рейс задержится.

Судя по is a very common Russian expression meaning judging by, based on, or if one goes by.

Grammatically, судя comes from the verb судить = to judge, but in modern Russian судя по is often learned as a fixed expression.

So:

• Судя по времени перехода = Judging by the transfer/passage time
• It sets up the basis for the conclusion in the main clause.

It is not tied to a specific subject like I judge or we judge. Russian often leaves that kind of thing implicit.

Because the preposition по here requires the dative case.

The noun время is irregular:

• nominative: время
• dative: времени

So:

• по времени = by the time / according to the time

This is very common after судя по:

• судя по погоде = judging by the weather
• судя по голосу = judging by the voice
• судя по времени = judging by the time

Перехода is genitive singular of переход.

That is because время is followed by a noun in the genitive to mean the time of something:

• время перехода = the time of the transfer / crossing / passage

So the structure is:

• по времени перехода
• literally: by the time of the transfer/passage

This is a very normal Russian noun phrase pattern:

• начало фильма = the beginning of the film
• конец недели = the end of the week
• время прибытия = time of arrival

That depends on context. Переход has several possible meanings, including:

• crossing
• passage
• transition
• transfer or connection in travel contexts

In a sentence about a рейс = flight/service/run, it may refer to something like:

• transfer time
• connection time
• the time needed to move between points
• a travel segment

So the exact English word depends on the situation. Russian often uses one word where English might choose different translations depending on context.

Because Судя по времени перехода is an introductory phrase attached to the main statement.

Russian usually separates this kind of phrase with a comma:

• Судя по прогнозу, завтра будет дождь.
• Судя по его голосу, он устал.
• Судя по времени перехода, ночной рейс задержится.

You can think of it as similar to English:

• Judging by the forecast, it will rain tomorrow.

It is a simple adjective + noun combination:

• ночной = night / overnight
• рейс = flight, route, run, service

Both are in the nominative singular masculine because рейс is the subject of the sentence.

Agreement:

• masculine singular noun: ночной рейс
• feminine singular noun: ночная смена
• neuter singular noun: ночное окно
• plural: ночные рейсы

So here:

• ночной matches рейс

Задержится is the future tense of задержаться, which means to be delayed or to get delayed.

So:

• рейс задержится = the flight will be delayed

This is a very natural way to say it in Russian.

Compare:

• Рейс задержится. = The flight will be delayed.
• Рейс будет задержан. = The flight will be delayed.
  This is also correct, but it is more formally passive in tone.
• Рейс задержат. = They will delay the flight.
  This focuses more on an unspecified agent.

Russian often prefers a verb like задержаться instead of a passive construction.

Yes, задержится is formally a reflexive verb because it has -ся, but here it does not mean the flight is literally delaying itself in the English sense.

In Russian, many verbs with -ся are used in ways that are not truly reflexive in English. Here it simply gives an intransitive meaning:

• задержать рейс = to delay a flight
• рейс задержится = the flight will be delayed

So -ся often helps turn a verb into something like:

• happen to itself
• become
• end up in that state

It is best to learn задержаться here as a normal vocabulary item meaning to be delayed.

It is future tense.

The verb задержаться is perfective, and perfective verbs do not normally have a true present tense. Their present-looking forms actually refer to the future.

So:

• задержится = will be delayed

Compare:

• imperfective: задерживаться = to be getting delayed / to be delayed repeatedly
• perfective: задержаться = to get delayed, to end up delayed

In this sentence, the speaker is making a prediction about a specific future event, so the perfective future is a good fit.

Yes, Russian word order is flexible.

The neutral order here is:

• Судя по времени перехода, ночной рейс задержится.

But other orders are possible depending on emphasis, for example:

• Ночной рейс, судя по времени перехода, задержится.
• Задержится, судя по времени перехода, ночной рейс.
  This last one is much less neutral and sounds stylistically marked.

The original version is the most natural if you are simply stating a conclusion based on some evidence.

A rough literal breakdown is:

• Судя = judging
• по = by / according to
• времени = time
• перехода = of the transfer/passage/crossing
• ночной = night / overnight
• рейс = flight/service
• задержится = will be delayed

So the structure is roughly:

Judging by the time of the transfer/passage, the overnight flight will be delayed.

That literal breakdown helps show the grammar, even if the best English translation might use slightly different wording depending on context.